feat (init): Migrating package flutter_sequence_animation to null safetty

.gitignore

+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+.pub-cache/
+.pub/
+build/
+
+# Android related
+**/android/**/gradle-wrapper.jar
+**/android/.gradle
+**/android/captures/
+**/android/gradlew
+**/android/gradlew.bat
+**/android/local.properties
+**/android/**/GeneratedPluginRegistrant.java
+
+# iOS/XCode related
+**/ios/**/*.mode1v3
+**/ios/**/*.mode2v3
+**/ios/**/*.moved-aside
+**/ios/**/*.pbxuser
+**/ios/**/*.perspectivev3
+**/ios/**/*sync/
+**/ios/**/.sconsign.dblite
+**/ios/**/.tags*
+**/ios/**/.vagrant/
+**/ios/**/DerivedData/
+**/ios/**/Icon?
+**/ios/**/Pods/
+**/ios/**/.symlinks/
+**/ios/**/profile
+**/ios/**/xcuserdata
+**/ios/.generated/
+**/ios/Flutter/App.framework
+**/ios/Flutter/Flutter.framework
+**/ios/Flutter/Flutter.podspec
+**/ios/Flutter/Generated.xcconfig
+**/ios/Flutter/app.flx
+**/ios/Flutter/app.zip
+**/ios/Flutter/flutter_assets/
+**/ios/Flutter/flutter_export_environment.sh
+**/ios/ServiceDefinitions.json
+**/ios/Runner/GeneratedPluginRegistrant.*
+
+# Exceptions to above rules.
+!**/ios/**/default.mode1v3
+!**/ios/**/default.mode2v3
+!**/ios/**/default.pbxuser
+!**/ios/**/default.perspectivev3

.metadata

+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: b1395592de68cc8ac4522094ae59956dd21a91db
+  channel: stable
+
+project_type: package

CHANGELOG.md

+## [0.0.1] - TODO: Add release date.
+
+* TODO: Describe initial release.

LICENSE

+TODO: Add your license here.

README.md

+# flutter_sequence_animation_null_safety
+
+A new Flutter package project.
+
+## Getting Started
+
+This project is a starting point for a Dart
+[package](https://flutter.dev/developing-packages/),
+a library module containing code that can be shared easily across
+multiple Flutter or Dart projects.
+
+For help getting started with Flutter, view our 
+[online documentation](https://flutter.dev/docs), which offers tutorials, 
+samples, guidance on mobile development, and a full API reference.

lib/flutter_sequence_animation_null_safety.dart

+library flutter_sequence_animation_null_safety;
+
+import 'package:flutter/material.dart';
+import 'package:meta/meta.dart';
+
+class _AnimationInformation {
+  _AnimationInformation({
+    this.animatable,
+    this.from,
+    this.to,
+    this.curve,
+    this.tag,
+  });
+
+  final Animatable? animatable;
+  final Duration? from;
+  final Duration? to;
+  final Curve? curve;
+  final Object? tag;
+}
+
+class SequenceAnimationBuilder {
+  List<_AnimationInformation> _animations = [];
+
+  /// Adds an [Animatable] to the sequence, in the most cases this would be a [Tween].
+  /// The from and to [Duration] specify points in time where the animation takes place.
+  /// You can also specify a [Curve] for the [Animatable].
+  ///
+  /// [Animatable]s which animate on the same tag are not allowed to overlap and they also need to be add in the same order they are played.
+  /// These restrictions only apply to [Animatable]s operating on the same tag.
+  ///
+  ///
+  /// ## Sample code
+  ///
+  /// ```dart
+  ///     SequenceAnimation sequenceAnimation = new SequenceAnimationBuilder()
+  ///         .addAnimatable(
+  ///           animatable: new ColorTween(begin: Colors.red, end: Colors.yellow),
+  ///           from: const Duration(seconds: 0),
+  ///           to: const Duration(seconds: 2),
+  ///           tag: "color",
+  ///         )
+  ///         .animate(controller);
+  /// ```
+  ///
+  SequenceAnimationBuilder addAnimatable({
+    @required Animatable? animatable,
+    @required Duration? from,
+    @required Duration? to,
+    Curve curve: Curves.linear,
+    @required Object? tag,
+  }) {
+    assert(to! >= from!);
+    _animations.add(new _AnimationInformation(
+        animatable: animatable!, from: from!, to: to!, curve: curve, tag: tag!));
+    return this;
+  }
+
+  /// The controllers duration is going to be overwritten by this class, you should not specify it on your own
+  SequenceAnimation animate(AnimationController? controller) {
+    int longestTimeMicro = 0;
+    _animations.forEach((info) {
+      int micro = info.to!.inMicroseconds;
+      if (micro > longestTimeMicro) {
+        longestTimeMicro = micro;
+      }
+    });
+    // Sets the duration of the controller
+    controller!.duration = new Duration(microseconds: longestTimeMicro);
+
+    Map<Object, Animatable> animatables = {};
+    Map<Object, double> begins = {};
+    Map<Object, double> ends = {};
+
+    _animations.forEach((info) {
+      assert(info.to!.inMicroseconds <= longestTimeMicro);
+
+      double begin = info.from!.inMicroseconds / longestTimeMicro;
+      double end = info.to!.inMicroseconds / longestTimeMicro;
+      Interval intervalCurve = new Interval(begin, end, curve: info.curve!);
+      if (animatables[info.tag] == null) {
+        animatables[info.tag!] =
+            IntervalAnimatable.chainCurve(info.animatable!, intervalCurve);
+        begins[info.tag!] = begin;
+        ends[info.tag!] = end;
+      } else {
+        assert(
+            (ends[info.tag!])! <= begin,
+            "When animating the same property you need to: \n"
+            "a) Have them not overlap \n"
+            "b) Add them in an ordered fashion");
+        animatables[info.tag!] = IntervalAnimatable(
+          animatable: animatables[info.tag!],
+          defaultAnimatable:
+              IntervalAnimatable.chainCurve(info.animatable!, intervalCurve),
+          begin: begins[info.tag],
+          end: ends[info.tag],
+        );
+        ends[info.tag!] = end;
+      }
+    });
+
+    Map<Object, Animation> result = {};
+
+    animatables.forEach((tag, animInfo) {
+      result[tag] = animInfo.animate(controller);
+    });
+
+    return new SequenceAnimation._internal(result);
+  }
+}
+
+class SequenceAnimation {
+  final Map<Object, Animation>? _animations;
+
+  /// Use the [SequenceAnimationBuilder] to construct this class.
+  SequenceAnimation._internal(this._animations);
+
+  /// Returns the animation with a given tag, this animation is tied to the controller.
+  Animation? operator [](Object key) {
+    assert(_animations!.containsKey(key),
+        "There was no animatable with the key: $key");
+    return _animations![key];
+  }
+}
+
+/// Evaluates [animatable] if the animation is in the time-frame of [begin] (inclusive) and [end] (inclusive),
+/// if not it evaluates the [defaultAnimatable]
+class IntervalAnimatable<T> extends Animatable<T> {
+  IntervalAnimatable({
+    @required this.animatable,
+    @required this.defaultAnimatable,
+    @required this.begin,
+    @required this.end,
+  });
+
+  final Animatable? animatable;
+  final Animatable? defaultAnimatable;
+
+  /// The relative begin to of [animatable]
+  /// If your [AnimationController] is running from 0->1, this needs to be a value between those two
+  final double? begin;
+
+  /// The relative end to of [animatable]
+  /// If your [AnimationController] is running from 0->1, this needs to be a value between those two
+  final double? end;
+
+  /// Chains an [Animatable] with a [CurveTween] and the given [Interval].
+  /// Basically, the animation is being constrained to the given interval
+  static Animatable chainCurve(Animatable parent, Interval interval) {
+    return parent.chain(new CurveTween(curve: interval));
+  }
+
+  @override
+  T transform(double t) {
+    if (t >= begin! && t <= end!) {
+      return animatable!.transform(t);
+    } else {
+      return defaultAnimatable!.transform(t);
+    }
+  }
+}
\ No newline at end of file

pubspec.lock

+# Generated by pub
+# See https://dart.dev/tools/pub/glossary#lockfile
+packages:
+  async:
+    dependency: transitive
+    description:
+      name: async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.5.0"
+  boolean_selector:
+    dependency: transitive
+    description:
+      name: boolean_selector
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
+  charcode:
+    dependency: transitive
+    description:
+      name: charcode
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0"
+  clock:
+    dependency: transitive
+    description:
+      name: clock
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
+  collection:
+    dependency: transitive
+    description:
+      name: collection
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.15.0"
+  fake_async:
+    dependency: transitive
+    description:
+      name: fake_async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0"
+  flutter:
+    dependency: "direct main"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
+  flutter_test:
+    dependency: "direct dev"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
+  matcher:
+    dependency: transitive
+    description:
+      name: matcher
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.12.10"
+  meta:
+    dependency: transitive
+    description:
+      name: meta
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.3.0"
+  path:
+    dependency: transitive
+    description:
+      name: path
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.8.0"
+  sky_engine:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.99"
+  source_span:
+    dependency: transitive
+    description:
+      name: source_span
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.8.0"
+  stack_trace:
+    dependency: transitive
+    description:
+      name: stack_trace
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.10.0"
+  stream_channel:
+    dependency: transitive
+    description:
+      name: stream_channel
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0"
+  string_scanner:
+    dependency: transitive
+    description:
+      name: string_scanner
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
+  term_glyph:
+    dependency: transitive
+    description:
+      name: term_glyph
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0"
+  test_api:
+    dependency: transitive
+    description:
+      name: test_api
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.2.19"
+  typed_data:
+    dependency: transitive
+    description:
+      name: typed_data
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.3.0"
+  vector_math:
+    dependency: transitive
+    description:
+      name: vector_math
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0"
+sdks:
+  dart: ">=2.12.0 <3.0.0"
+  flutter: ">=1.17.0"

pubspec.yaml

+name: flutter_sequence_animation_null_safety
+description: Composite together any animation with this robust and simple to use package.
+version: 3.0.1
+author: Norbert Kozsir <kozsir.norbert@gmail.com>
+homepage: https://github.com/Norbert515/flutter_sequence_animation
+
+environment:
+  sdk: ">=2.12.0 <3.0.0"
+  flutter: ">=1.17.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+
+# For information on the generic Dart part of this file, see the
+# following page: https://dart.dev/tools/pub/pubspec
+
+# The following section is specific to Flutter.
+flutter:
+
+  # To add assets to your package, add an assets section, like this:
+  # assets:
+  #   - images/a_dot_burr.jpeg
+  #   - images/a_dot_ham.jpeg
+  #
+  # For details regarding assets in packages, see
+  # https://flutter.dev/assets-and-images/#from-packages
+  #
+  # An image asset can refer to one or more resolution-specific "variants", see
+  # https://flutter.dev/assets-and-images/#resolution-aware.
+
+  # To add custom fonts to your package, add a fonts section here,
+  # in this "flutter" section. Each entry in this list should have a
+  # "family" key with the font family name, and a "fonts" key with a
+  # list giving the asset and other descriptors for the font. For
+  # example:
+  # fonts:
+  #   - family: Schyler
+  #     fonts:
+  #       - asset: fonts/Schyler-Regular.ttf
+  #       - asset: fonts/Schyler-Italic.ttf
+  #         style: italic
+  #   - family: Trajan Pro
+  #     fonts:
+  #       - asset: fonts/TrajanPro.ttf
+  #       - asset: fonts/TrajanPro_Bold.ttf
+  #         weight: 700
+  #
+  # For details regarding fonts in packages, see
+  # https://flutter.dev/custom-fonts/#from-packages

test/flutter_sequence_animation_null_safety_test.dart

+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('adds one to input values', () {
+  });
+}